The present invention relates to a method for performing route optimization between two nodes in network based mobility management, wherein each of said two nodes is associated with an access network via attachment to an access router, said access routers having directly or indirectly assigned a Mobility Access Gateway (MAG) that signals the node's presence to a Mobility Anchor (MA) which maintains the current IP address information along with location information of said node.
Nowadays, IP-based mobility management protocols, with Mobile IP client functionality residing in the host's/mobile node's (MN) stack, such as Mobile IPv4 or Mobile IPv6, are widely spread. These client-based (or host-based) mobility management architectures require the MN to take care of mobility-related signalling with the corresponding Home Agent (HA).
However, there are several classes of nodes which do not support Mobile IP. Currently, the Internet Engineering Task Force (IETF) is discussing and specifying solutions for network-based localized mobility management (NetLMM), providing mobility to such nodes which do not support any mobility management protocol. Compared to the above mentioned host-based mobility protocols, solutions for network-based mobility management relocate client control functions for mobility management from the mobile node to the network's access router(s).
Besides the provision of mobility to nodes which do not support any mobility management protocol, network-based mobility solutions are envisioned, as they are widely implementation independent and can be employed without significant changes with different access technologies. In contrast, prior art cellular networks imply client-based mobility management and are in general specifically designed for certain kinds of access networks and technologies.
A crucial task in connection with mobility management is the finding and set up of an optimized route for data traffic between two mobile nodes. To support efficient routing of data packets between two MNs, which are under control of a single or different MAs, packets can be routed directly between the associated MAGs instead of traversing always the MAs. For instance, Mobile IPv6 has support for route optimization, to allow data packets travelling a more efficient path between communicating hosts without traversing always the Home Agent (HA). Set up of route optimization in Mobile IPv6 is entirely controlled by the end nodes themselves. On the other hand, Mobile IPv4 makes use of a Home Agent (HA) to initiate setting up direct routes between a MN and a Correspondent Node (CN) in the network. Both solutions consider sending the MN's location information to the CN. In Mobile IPv6, the MN itself sends the location information to the CN, whereas in Mobile IPv4, the Home Agent sends the MN's location information to the CN.
Support for route optimization (RO) in a NetLMM-enabled domain can be achieved similar to how Mobile IPv6 establishes route optimization. Assuming all mobility control has been relocated from the MN to the MAG, the MAG can send signaling to the CN to notify the MN's location. This enables the CN to send data packets directly towards the MN via the associated MAG. The specification for route optimization in known standards, such as for Mobile IPv6, is sufficient to support RO between one MN and one CN. Even support for RO between two MNs is possible. However, efficient support of RO between two MNs in complex mobility scenarios is not yet possible.